The advancement of technology in the information recording field is remarkable, and research and development are energetically ongoing for high density recording and regeneration and high-speed access of optical memories using lights and magneto-optical disk memories, for example. Research and development for utilizing the features of such optical disk memories are advancing, and in Japanese Patent Application Laid-Open No. H6-202820 or in the Journal of the Institute of Television Engineers of Japan, Vol. 46, No. 10, pp. 1319-1324 (1992), for example, a concurrent ROM-RAM optical disk which allows the simultaneous regeneration of ROM (Read Only Memory)—RAM (Random Access Memory) is disclosed.
Such an optical information recording medium which allows simultaneous regeneration of ROM-RAM has a characteristic whereby ROM-RAM simultaneous regeneration, which is impossible with a magnetic disk, is possible, in addition to a characteristic whereby storage capacity double a normal optical disk memory can be obtained.
For example, according to the prior art, on the optically transparent substrate where phase pits are formed in a spiral or concentric manner, an optical information recording medium on which magneto-optical recording film is formed is used. And light is condensed almost to the diffraction limit from the optical pickup, is irradiated onto the optical information recording medium, light returned from this optical information recording medium is modulated by the phase pits and light intensity thereof is regenerated as a ROM signal. And the differential amplitude in the polarization direction when the return light is modulated by the magneto-optical recording film is regenerated as a RAM signal.
And a magnetic head, for applying the magnetic field on the optical information recording medium, is installed on the optical pickup, and the RAM signals are recorded on the magneto-optical recording film by changing at least one of condensed light from the optical pickup and the magnetic field.
In this prior art, it is theoretically possible to regenerate ROM and RAM simultaneously by one optical pickup and record the data in the RAM while regenerating the data in the ROM. However various aspects require improvement to actually utilize these superb functions.
For example, it is desirable to record user data to be sequentially input in the RAM for a medium where such stream information as music and image information is recorded as ROM information while regenerating only ROM information or both ROM and RAM information of the medium. In other words, while regenerating music and images (e.g. scenery, maps) recorded as ROM information, such as a CD (Compact Disk) without interruption, a singing voice and commentary are recorded in RAM, or while regenerating music and images (e.g. scenery, maps) recorded as ROM information and RAM information without interruption, the playing sound of an instrument, new map and road information are recorded in RAM.
In such a case, with the prior art alone, recording in RAM while regenerating ROM is possible, but it is difficult to record RAM information in a predetermined relationship where regenerated ROM information and recorded RAM information are linked.
Also in the prior art, simultaneous regeneration of ROM and RAM is possible, but the data cannot be recorded in the RAM during this simultaneous regeneration. For the user, it is desirable that information can be input and recorded in the optical information recording medium without interruption while regenerating ROM information or already recorded RAM information.